Despite great improvements in the detection of cancer in the last few decades, non-invasive early detection is still a challenge. Optical imaging is a modality that offers high spatio-temporal resolution, millimeters in depth of imaging, spectral resolution of tissue or contrast agent signals, and relative simplicity that would permit its use in real time at a physician's office or operating room. Despite these benefits, its application to the detection of developing tumors is limited due to the lack of optical contrast between normal and cancerous tissue. In the present proposal, InnoSense LLC aims to develop and perform preliminary in vitro and in vivo evaluation of injectable, long-circulating, targeted enzymatically-activated nanoparticles (EANPs) that act as cancer-specific contrast agents for non-invasive optical imaging of tumors. These nanoparticles, based on proven biocompatible and biodegradable polymers, will contain quenched near infra- red (NIR) fluorescent molecules that are activated upon interaction with target enzymes that are overexpressed in tumor tissue. The specificity of these nanoparticles to tumors will be increased by taking advantage of the enhanced permeability and retention effect that permits accumulation of nanoparticles at tumor tissue, and by the incorporation of antibodies specific to cancer biomarkers. The use of nanoparticles to improve the biodistribution and payload of the fluorescent molecules to tumors, combined with the cancer-specific enzyme-triggered development of NIR signal is expected to result in significantly increased signal-to-background levels in comparison to other contrast agent systems, thus improving the specificity and sensitivity of non-invasive optical detection. The biocompatibility and specificity of antibody- lacking and antibody-bound EANPs will be evaluated in vitro in normal and cancer cells. Optical contrast enhancement will be evaluated as a function of nanoparticle formulation, concentration and depth in tissue phantoms and in animal models of cancer. This project will be performed in collaboration with Dr. Bernard Choi, Assistant Professor of the Department of Biomedical Engineering and the Beckman Laser Institute of the University of California, Irvine. Upon completion of the Phase I feasibility study, a Phase II project will center on the optimization of EANP preparation, reproducibility, and scale up, and rigorous evaluation in animal models of cancer to determine optimal dose, NIR development time, and achievable imaging depth and spatial resolution. PUBLIC HEALTH RELEVANCE: Despite great improvements in the detection of cancer in the last few decades, non-invasive early detection of tumors is still a challenge. Optical imaging is a modality that offers high spatial and temporal resolution, the ability to detect and separate signals from tissue or contrast agents, millimeters in depth of imaging, and relative simplicity that would permit its use at a physician's office or operating room. Despite these benefits, its application to the detection of developing tumors is limited due to the low contrast between normal and cancerous tissue. In the present proposal, InnoSense LLC aims to develop and evaluate injectable, long-circulating, targeted enzymatically-activated nanoparticles (EANPs) that act as cancer-specific contrast agents for non-invasive optical imaging of tumors. EANPs, based on proven non-toxic polymers, will contain dormant fluorescent molecules that are activated upon interaction with enzyme molecules that are present in high levels in tumor tissue. The high payload of EANPs, together with their cancer-triggered activation will lead to high signal-to-background levels that improve the sensitivity of optical detection. This research will not only result in the development of a safe and effective option for non-invasive imaging of cancerous tissue, but will also further the body of scientific knowledge in the area of nanoparticle-based contrast agents and biomaterials.